A good number of the jokes in Walk Hard: The Dewey Cox Story are available for your amusement right now, well ahead of the film’s December 21 theatrical-release date. Just hit up check out the trailer, which condenses what writer Judd Apatow and director Jake Kasdan have to say about music bio-pics into a four-minute gag reel that covers nearly all the bases of their 92-minute movie.

Where Walk Hard’s trailer comes up short is in the music department — but even the complete movie, with its quick cuts and swift narrative, doesn’t do justice to the songs Kasdan and Apatow commissioned (and in some instances wrote) to flesh out the life story of Dewey Cox, the Johnny Cash/Brian Wilson/Ray Charles amalgam played (and sung) by John C. Reilly. To appreciate their value, you’ve gotta consult the Sony soundtrack album, which collects 15 of Cox’s would-be greatest hits, from the title track, a rockabilly rave-up inspired by Cash’s Sun Studio stuff, to “Black Sheep,” an over-the-top orchestral-pop production indebted to Wilson’s Smile.

The tunes are funny: “Let’s Duet” boasts more sexual double entendres than an issue of Maxim, and “Let Me Hold You (Little Man)” elevates junior-high-level comedy to new heights. But most of them are also pitch-perfect genre exercises crafty enough to make the guys in Ween or They Might Be Giants jealous. Scan the liner notes and you’ll see Kasdan and Apatow know that the key to satire is authenticity — their crew of songwriters includes such real-world pros as Marshall Crenshaw, Van Dyke Parks, Dan Bern, and Mike Viola.

And their work has value beyond the humor. “Guilty As Charged” is an excellent “Ring of Fire”–style shuffle complete with tart mariachi horns; “Black Sheep” offers a typically whimsical Parks string chart; “Beautiful Ride” has a killer pre-chorus in which Reilly emphasizes the need to “make a little music every day till you die.” As a singer, Reilly is a revelation, a big-lunged vocal impressionist more than capable of channeling each of the pop stars the film skewers. In the unlikely event that this guy’s big-screen work dries up, his musical-theater future is secure. (He starred in the title role of the musical Marty at the Huntington Theatre Company in 2002.)

Rufus Wainwright is a different kind of impressionist: on Rufus Does Judy at Carnegie Hall, a new double-disc live set recorded last summer in New York, he sets out to pay homage to Judy Garland by re-creating her famous 1961 Carnegie Hall concert. Yet as anyone who’s familiar with his songwriting knows, Wainwright isn’t really interested in paying homage to anyone but himself; he’s one of pop’s most compelling egomaniacs, and that doesn’t change just because he’s singing someone else’s material. So Rufus Does Judy is less about Rufus doing Judy (in the way that Walk Hard is about John doing Johnny, for instance) than it is about Rufus doing Rufus doing Judy as if she were doing Rufus.

That’s no cause for complaint — you’re still getting deathless songs, gorgeous arrangements, handsome singing, and some excellent banter. (“I feel like Judy Garland’s secretary,” Wainwright says after complaining about the effort required to memorize not only lyrics but also — horror of horrors — the names of his bandmembers.) And as Garland would no doubt agree, you can’t fit all that in a trailer.

Bottle rocket Who exactly is Charlyne Yi? Two years ago, she appeared — seemingly from out of nowhere — in a brief but memorable turn in Judd Apatow's Knocked Up. A closer look at Apatow's new Funny People , however, might provide a clue as to where he discovered her.

The Promotion Reilly is an actor who excels at both realism and caricature — too bad the director doesn’t have the chops to take advantage either way.

Annie variations The Bang Group's performance at Concord Academy Thursday night wrapped the audience in rings of intimacy and surprise. Choreographer/director David Parker, acting as MC, paid loving tribute to Summer Stages Dance, where he and the company have appeared and taught for 10 years.

19. Judd Apatow and Friends In their non-probing, unprovocative films, the characters this Hollywood comedic mafia chooses to celebrate are homely, smoke a lot of pot, and watch way too much porn. We get it. Yes, Apatow, Seth Rogen, and Jonah Hill aren’t exactly anyone’s dream dates based on physical attributes alone. But we saved a special unsexy spot for this threesome based on the inescapable fact that we’re completely sick of getting inundated with their repetitive shtick. Apatow gets bonus unsexy points for the right-wing current bubbling beneath his flicks.

DEVO | SOMETHING FOR EVERYBODY | July 01, 2010 Given the theory of de-evolution these Ohio brainiacs began expounding more than 30 years ago, it makes a sad kind of sense that Devo's first album since 1990's Smooth Noodle Maps offers such a charmless, base-level version of the band's synth-addled new wave.